Development, characterization and evaluation of composite adsorbent for the adsorption of crystal violet from aqueous solution: Isotherm, kinetics, and thermodynamic studies

Abstract The jeopardy of the synthetic dyes effluents on human health and the environment has swiftly aggravated, threatening human survival. Hence, sustained studies have figured out the most acceptable way to eliminate this poisonous contaminant. Thereby, our investigation aimed to fabricate montmorillonite/magnetic NiFe 2 O 4 @amine-functionalized chitosan (MMT-mAmCs) composite as a promising green adsorbent to remove the cationic methylene blue (MB) and crystal violet (CV) dyes from the wastewater in neutral conditions. Interestingly, MMT-mAmCs composite carries high negative charges at a wide pH range from 4 to 11 as clarified from zeta potential measurements, asserting its suitability to adsorb the cationic contaminants. In addition, the experimental study confirmed that the optimum pH to adsorb both MB and CV was pH 7, inferring the ability of MMT-mAmCs to adsorb both cationic dyes in simple process conditions. Furthermore, the ferromagnetic behavior of the MMT-mAmCs composite is additional merit to our adsorbent that provides facile, fast, and flawless separation. Notably, the as-fabricated composite revealed an auspicious adsorbability towards the adsorptive removal of MB and CV, since the maximum adsorption capacity of MB and CV were 137 and 118 mg/g, respectively. Moreover, the isotherm and kinetic investigatins depicted that the adsorption of both cationic dyes fitted Langmuir and Pseudo 2nd order models, respectively. Besides, the advanced adsorbent preserved satisfactory adsorption characteristics with maximal removal efficacy exceeding 87% after reuse for ten consecutive cycles. More importantly, MMT-mAmCs efficiently adsorbed MB and CV from real agricultural water, Nile river water and wastewater samples at the neutral pH medium, reflecting its potentiality to be a superb reusable candidate for adsorptive removal cationic pollutants from their aquatic media. 

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Efficient removal of noxious methylene blue and crystal violet dyes at neutral conditions by reusable montmorillonite/NiFe2O4@amine-functionalized chitosan composite

Highly efficient adsorbent for removal of Crystal Violet Dye from Aqueous Solution by CaAl/LDH supported on Biochar

This study reported the desorption of adsorbed crystal violet (CV) dye on the argan nutshell (ANS) and almond shell (AS) using nitric acid (HNO3) as a desorbing agent and their reusability to remov...

Regeneration of argan nutshell and almond shell using HNO3 for their reusability to remove cationic dye from aqueous solution

Towards the sustainable and circular bioeconomy: Insights on spent coffee grounds valorization.

Agricultural waste can be exploited for the adsorption of dyes, due to their low cost, availability, cost-effectiveness, and efficiency. In this study, we were interested in the elimination of crystal violet dye, from aqueous solutions, by adsorption on almond shell-based material, as a low-cost and ecofriendly adsorbent. The almond shells were first analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction; then, the influence of adsorbent dose, initial dye concentration time, and pH were studied to assess adsorption capacity under optimal experimental conditions. Experimental results indicate that almond shell adsorbent removes about 83% of the dye from the solutions at room temperature and in batch mode; the kinetic study showed that the equilibrium time is about 90 min, and the model of pseudo-second order could very well describe adsorption kinetics. The modulation of adsorption isotherms showed that retention follows the Langmuir model. The thermodynamic study has shown that the adsorption is endothermic (ΔH° > 0) and spontaneous (ΔG° < 0).

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Adsorption of Crystal Violet onto an Agricultural Waste Residue: Kinetics, Isotherm, Thermodynamics, and Mechanism of Adsorption

Industrial discharges loaded with heavy metals present several problems for aquatic ecosystems and human health. In this context, the present study aims to evaluate the potential of raw spent coffee grounds to remove chromium from an aqueous medium. A structural and textural study of coffee grounds was carried out by FTIR, XRD, and TGA analysis. The optimum conditions for the removal of Cr(VI), for a solution with an initial concentration of 100 mg/l, were adsorbent dose 2.5 g/l, pH 4.0, and contact time 90 min. The adsorption equilibrium results show that the Langmuir isotherm best describes the process with an adsorption capacity of 42.9 mg/g and that the adsorption kinetics follows the pseudosecond-order model. The calculated thermodynamic parameters showed that the adsorption is exothermic and spontaneous. The activation energy value (Ea) indicated that the retention is physisorptive in nature. The regeneration of the adsorbent was carried out by three eluents, among which HCl was the best. Finally, a brief cost estimation showed the great potential of coffee grounds as a low-cost adsorbent.

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Assessment of Untreated Coffee Wastes for the Removal of Chromium (VI) from Aqueous Medium

Characterization and adsorption capacity of four low-cost adsorbents based on coconut, almond, walnut, and peanut shells for copper removal

In recent years, the removal of dyes has emerged as a significant problem that attracted several researchers. The search for green and eco-friendly adsorbents has been a never-ending task in environmental protection to overcome this issue. Herein, almond shells (AS) were used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The AS was characterized using several techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Adsorption experiments were carried out under different pH, temperature, and AS particle size conditions. Kinetic and isothermal studies revealed that MO adsorption on the AS reached equilibrium at 90 min, following the pseudo-second-order (PSO) kinetic model. The Langmuir adsorption isotherm was found the suitable adsorption model for MO adsorption on AS, showing a maximum adsorption capacity of 15.63 mg/g. Thermodynamic parameters such as the change in standard enthalpy (ΔH°), the change in standard entropy (ΔS°), and the change in standard free energy (ΔG°) indicated that the MO dye adsorption process is non-spontaneous, endothermic, and physical, which was further confirmed from FTIR analysis of AS samples after adsorption. The contaminated sludge was converted into biochar by slow pyrolysis at a temperature of 400 °C for 2 h. Biochar has been exploited for the manufacture of combustible briquettes.

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Efficient Adsorption Removal of an Anionic Azo Dye by Lignocellulosic Waste Material and Sludge Recycling into Combustible Briquettes

This work examines the possibility of removing the crystal violet (a cationic dye), used in the dyeing of cotton, wood, and silk, onto untreated coffee waste. The influence of various experimental parameters on the adsorption of crystal violet has been analysed: pH, adsorbent dose and initial dye concentration. Optimum adsorption of crystal violet took place at pH 6 and at lower temperatures. Further, the adsorbent was characterised by Fourier Transform Infrared Spectroscopy (FTIR). FTIR analysis revealed the presence of several functional groups that are responsible for the adsorption process. Adsorption equilibrium follows Langmuir’s model with maximum retention of 63.3 mg/g. The kinetics of the crystal violet adsorption were studied using the pseudo-first order and pseudo-second order equations. Adsorption of the dye can be described by pseudo-second order kinetics, reaching the equilibrium at 40 min. The value of the activation energy shows that adsorption is physisorption. Weber-Morris model indicates that this adsorption occurs in two steps. Thermodynamic parameters suggest that the adsorption is spontaneous and exothermic.

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Ilyasse Loulidi

Papers

Adsorption of Crystal Violet onto an Agricultural Waste Residue: Kinetics, Isotherm, Thermodynamics, and Mechanism of Adsorption

Assessment of Untreated Coffee Wastes for the Removal of Chromium (VI) from Aqueous Medium

Characterization and adsorption capacity of four low-cost adsorbents based on coconut, almond, walnut, and peanut shells for copper removal

Efficient Adsorption Removal of an Anionic Azo Dye by Lignocellulosic Waste Material and Sludge Recycling into Combustible Briquettes

Kinetic, Isotherm and Mechanism Investigations of the Removal of Basic Violet 3 from Water by Raw Spent Coffee Grounds